Metallurgical addition product

ABSTRACT

A metallurgical charge product comprising a package containing an intimate mixture of nickel oxide sinter and petroleum coke.

United States Patent [191 Pargeter et a1.

[451 Apr. 15, 1975 1 1 METALLURGICAL ADDITION PRODUCT [75] Inventors:John K. Pargeter, New York, N.Y.;

Loris M. Diran, Hackensack; Francis J. Hennion, Prospect Park, both ofNJ.

[73] Assignee: The International Nickel Company,

Inc., New York, NY.

[22] Filed: Sept. 21, 1973 [21] Appl. No.: 399,467

[52] US. Cl. 75/129; 75/53; 75/93 G; 75/94 [51] Int. Cl C22c l/00; C22b9/10 [58] Field of Search 75/52-58, 82, 75/94, 3-5, 129, 93 G [56]References Cited UNITED STATES PATENTS 1,275,449 8/1918 Lemon 75/93 G2,086,756 7/1937 Whitaker 75/53 2,333,741 11/1943 Reeder 75/53 2,397,4183/1946 Howard 75/56 2,550,735 5/1951 Tour 75/93 G 2,698,229 12/1954Lindsley. 75/82 2,881,068 4/1959 Bergh 75/53 2,913,337 11/1959 Kretz75/56 3,272,616 9/1966 Queneau 75/82 3,436,209 1/1969 Lojas 75/533,459,540 8/1969 Tisda1e..... 75/129 3,681,050 8/1972 Kazufusa 75/533,769,002 10/1973 O Neill 75/82 Primary ExaminerL. Dewayne RutledgeAssistant ExaminerPeter D. Rosenberg [57] ABSTRACT A metallurgicalcharge product comprising a package containing an intimate mixture ofnickel oxide sinter and petroleum coke.

7 Claims, No Drawings METALLURGICAL ADDITION PRODUCT The presentinvention is concerned with a product useful in the formulation of metalfurnace charges and. more particularly, with a product for make up ofnickel content in furnace charges for manufacture of stainless steel andother nickel containing products.

It is well known in the art that nickel in various forms including oxidesinter has been used to provide the nickel content for stainless steelmeltdown charges. Recently, a number of manufacturers of stainless steeland other chromium-containing alloys have adopted the practice asdescribed in U.S. Pat. No. 3.046,l07 to Nelson et al. July 24, 1962 andin U.S. Pat. No. 3,252,790 to Krivsky, May 24. 1966 of decarburizingchromiumcontaining alloy metals by means of mixtures of argon and oxygenwith the relative proportion of argon being increased as the percentageof carbon in the melt decreases. According to some workers in the field,the advent of this process, known as the AOD process. has made it lessdesirable to include oxidic forms of nickel in stainless steel charges.The present application is directed to a novel means whereby a nickeloxide sinter product can be used with advantage in stainless steelcharges as well as in charges for other alloys containing chromium.

The invention is also directed to a means for overcoming the objectionsto use of nickel oxide sinter in the foundry industry where there is agrowing trend to induction furnace melting. Such furnaces are notsuitable for use with nickel oxide as a source of nickel because theyare unable to handle slag or. a violent boil caused by reduction ofnickel oxide by carbon in the presence of a molten phase. A furtherserious objection to the use of nickel oxide sinter in foundryoperations is the reaction of readily oxidizable elements in the scrapcharged to the furnace with the oxygen in nickel oxide sinter. In thehighly competitive foundry industry. there is a strong desire topreserve all alloying element units contained in the scrap in order tominimize addition of high-cost ferro-alloys and other forms of alloyingelements. The present application is directed toward a novel meanswhereby nickel oxide sinter can be used to advantage in the foundryindustry where, until now, only purer forms of nickel were suitable.

It is a object of the invention to provide a means involving a packagedproduct and process whereby nickel oxide sinter can be employed ascharge material in meltdown of stainless steel compositions adapted tobe refined by the AOD process.

Other objects and advantages will become apparent from the followingdescription.

Generally speaking. the present invention contemplates a packagethermally resistant to but permeable to gas at temperatures of about600C. to about l000C., non-contaminating with respect to achromium-Containing alloy metals and containing particulate richmodifications thereof marketed in the physical form of granules orpowder:

The term petroleum coke" means the residue from the destructivedistillation of petroleum.

In using the product of the'present invention, the package is placedalong with scrap iron or steel, ferrochrome and the like in an are orinduction furnace, in a location away from the direct heat of the are orother heating means and preferably in the middle of or near the top ofthe charge. Power for meltdown is then applied resulting in heating thepackage. In the temperature range of about 600C. to about 1000C. thepetroleum coke (or volatiles released therefrom) reacts with the nickeloxide sinter in the confines of the package to reduce the nickel oxideto metallic nickel and produces a carbon oxide-containing gas whichescapes from the package. The packaged product is highly advantageous inthat it avoids segregation of high melting nickel oxide in the bath. ltavoids loss of alloy ingredients such as silicon and chromium byeliminating need for reduction of nickel oxide by these elements. Itminimizes slag formation. It is a source of heat and simultaneously itproduces a gas during melt-down which can aid in protecting the chargefrom undue oxidation. Those skilled in the art will note that thetemperature range of reduction within the package confines i.e., amaximum of about l0O0C. to ll00C. is lower than the usual melting rangeof stainless steels. Thus when the stainless steel (or otherchromium-containing, nickel-containing alloy) is fully melted thepackaged product is essentially all metallic nickel.

While the term package" is intended to be sufficiently broad to includeitems such as self-supporting briquettes sintered flux-coated masses,etc., it is highly advantageous to employ as the package a simpleventable steel can having perforations, sealed for shipping purposes bya thermally decomposible seal, e.g., cardboard, polyethylene, etc. Onemajor producer of nickel oxide sinter in Canada employs a steel can of50 pounds (about 22.7 kg.) net for shipment of nickel oxide sintercontaining about percent by weight of nickel. [t is specificallycontemplated in accordance with the present invention to include in sucha can finely divided petroleum coke in an amount of about 6% pounds(about 2.85 kg.) along with a small amount of an adhering agent. e.g.,bunker C oil. in order to minimize segregation of the nickel oxidesinter and the petroleum coke. Of course other size cans can be used.For example, for use in induction furnaces a cylindrical, steel can ofabout 12.7cm diameter and about 15.2cm high is convenient. The can covercan be perforated and backed by a cardboard disk. When the can is heatedalong with the charge the cardboard disk chars thereby allowing forescape of gaseous products of reduction from the can. Upon melt-down thecan forms part of the iron charge of the melt. With nickel oxide sintercontaining about 75 percent by weight of nickel about 12 parts by weightof petroleum coke are used per 100 parts by weight of sinter. Withnickeloxide sinter containing about percent by weight of nickel about 5or 6 parts by weight of petroleum coke are used per parts by weight ofsinter. Also, if desired, reducible oxide other than nickel oxidesinter. e.g.. FeO Fe O (Fe, Ni) O, (a product formed by roastingpentlandite), CoO or the like can be included in the package along withnickel oxide with an appropriate allowance of petroleum coke being made.

In order to give those skilled in the art a better understanding andappreciation of the invention. the following examples are given:

EXAMPLE I Fifty pounds (about 22.7 kg) of nickel oxide sinter containingabout 75 percent by weight of nickel are wetted with a small amount ofbunker C oil and mixed with 6 pounds (about 2.73 kg) of petroleum cokeground to pass through a 60 mesh (about 23 openings/cm) screen. Themixture is then packed in a ventable steel can having perforationscovered over by a seal. The thus formed package along with others of thesame form is introduced into an arc-furnace stainless steel charge in aposition away from direct contact with the arc. Power is applied and atmelt-down it is found that the stainless steel melt contains essentiallyall of the nickel charged as oxide sinter with very little loss of othermore easily oxidizable elements to the slag.

EXAMPLE ll A nickel-chromium-containing cast iron was melted in aninduction furnace using as the charge nickel a briquette packagedmixture of 100 parts by weight of nickel oxide sinter containing about75 percent nickel. about 12.5 parts by weight of petroleum coke andabout 1 part by weight of methyl cellulose. The briquettes were placedin the upper portion of the charge and melt down was achieved after 50minutes of power on. The casting appearance and quality wasjudgedtypical of the alloy. Nickel was recovered in the alloy to the extent of99% and no loss of chromium originally present in the charge along withthe nickel oxide sinter was detected. These percentage recoveries ofnickel and chromium are typical of recoveries not only in cast ironmelting but also in stainless steel melting. In three melts of type 304stainless steel. chromium recoveries were between 96 percent and 100percent and nickel recoveries were between 98.4 and 100 percent.

In carrying out the process of the present invention (i.e., using thenovel packaged nickel oxide sinter product) it is important that thereaction of the nickel oxide and petroleum coke be essentially completeprior to the presence in the furnace of any significant amount of moltenmetal. lf reduction of sinter is still proceeding when molten metal ispresent a dangerously violent boil can occur.

Although the present invention has been described in conjunction withpreferred embodiments. it is to be understood that modifications andvariations may be resorted to without departing from the spirit andscope of the invention. as those skilled in the art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the invention and appended claims.

We claim:

1. A metallurgical addition package comprising a ventable steel canpermeable to gas at about 600C. to about l000C., and non-contaminatingwith respect to a chromium-containing alloy melt packed with particulatenickel oxide sinter along with a quantity of finely divided petroleumcoke in an amount stoichiometrically equivalent for reducing purposes tosaid nickel oxide. the petroleum coke being intimately mixed with andadherent to said particulate nickel oxide sinter.

2. A metallurgical process comprising charging a metallurgical additionpackage containing nickel oxide sinter and a quantity of petroleum cokestoichiometrically equivalent for reducing purposes to said nickel oxidesinter into a furnace along with other alloying ingredients and causingthe nickel oxide sinter to be reduced by said petroleum coke insaidpackage prior to the presence of any significant amount of moltenmetal in said furnace.

3. A product as in claim 1 wherein the nickel oxide sinter containsabout percent nickel by weight.

4. A product as in claim 1 which also contains a reducible metal oxideother than nickel oxide sinter.

5. A product as in claim 1 wherein the nickel oxide sinter containsabout percent nickel by weight.

6. A process as in claim 2 wherever the nickel oxide sinter containsabout 75 percent nickel.

7. A process as in claim 2 wherein the nickel oxide sinter containsabout 90 percent nickel.

1. A METALLUGICAL ADDITON PACKAGE COMPRISING A VENTABLE STEEL CANPERMEABLE TO GAS AT ABOUT 600*C. TO ABOUT 1000*C., AND NON-CONTAMINATINGWITH RESPECT TO A CHROMIUMCONTAINING ALLOY MELT PACKED WITH PARTICULATENICKEL OXIDE SINTER ALONG WITH A QUANTITY OF FINELY DIVIDED PERTROLEUMCOKE IN AN AMOUNT STOICHIOMETRICALLY EQUIVALENT FOR REDUCING PURPOSES TOSAID NICKEL OOXDE, THE PERTROLEUM COKE BEING INTIMATELY MIXED WITH ANADHERENT TO SAID PARTICULATE NICKEL OXIDE SINTER.
 2. A metallurgicalprocess comprising charging a metallurgical addition package containingnickel oxide sinter and a quantity of petroleum coke stoichiometricallyequivalent for reducing purposes to said nickel oxide sinter into afurnace along with other alloying ingredients and causing the nickeloxide sinter to be reduced by said petroleum coke in said package priorto the presence of any significant aMount of molten metal in saidfurnace.
 3. A product as in claim 1 wherein the nickel oxide sintercontains about 75 percent nickel by weight.
 4. A product as in claim 1which also contains a reducible metal oxide other than nickel oxidesinter.
 5. A product as in claim 1 wherein the nickel oxide sintercontains about 90 percent nickel by weight.
 6. A process as in claim 2wherever the nickel oxide sinter contains about 75 percent nickel.
 7. Aprocess as in claim 2 wherein the nickel oxide sinter contains about 90percent nickel.